در این پایان نامه ابتدا شرط برد پایدار $ n $ را معرفی کرده، سپس حلقه های تبادلی را تعریف می کنیم و شرایط لازم و کافی برای این که حلقه تبادلی $ r $، در شرط برد پایدار $ n $ صدق کند را بیان می کنیم. نشان می دهیم که حلقه تبادلی $ r $، در شرط برد پایدار $ n $ صدق می کند اگر و تنها اگر برای هرعنصر منظم $ ain r ^{n} $، عنصر تک پیمانه ای مانند $ u in r ^{n} $ وجود داشته باشد به طوری که $ au in r $ یک ...

with the increasing population and the need for more food, as well as with the development of science and technology, human approach to unnatural and often chemical inputs to increase agricultural production has been a great expansion and problems such as increased cancers, chronic diseases has created environmental pollution. implementation of organic organic is a solution to these problems . ...

in this thesis, a better reaction conditions for the synthesis of spirobarbiturates catalyzed by task-specific ionic liquid (2-hydroxy-n-(2-hydroxyethyl)-n,n-dimethylethanaminium formate), calcium hypochlorite ca(ocl)2 or n-bromosuccinimide (nbs) in the presence of water at room temperature by ultrasonic technique is provided. the design and synthesis of spirocycles is a challenging task becaus...

abstract venlafaxine, 1–[2–(dimethylamino)–1–(4–methoxyphenyl) ethyl]cyclohexanol hydrochloride is a novel non-tricyclic antidepressant. venlafaxine is a second generation antidepressant drug, has a neuropharmacologic profile distinct from that of existing antidepressants including tricyclic compounds, selective serotonin reuptake inhibitors and monoamine oxidase inhibitors. venlafaxine impart...

feminine voice and narratology in wuthering heights wuthering heights as a general "bronte" work has extraordinary dimensions to it which can make it focal to different ways of interpretation. among other differences the issue of narrative voice is essential in understanding the ultimate purpose of wuthering heights. emily bronte uses different narrators from various focal points speaking of m...

within communicative, interactive, and learner-centered framework of language teaching and learning, students need to learn four skills of listening, speaking, reading, and writing for their educational success. but of all the language skills, reading enjoys a paramount significance in so many second or foreign language academic contexts. in spite of its importance, language learners still have...

textbooks play a crucial role in language learning classrooms. the problem is that among the great quantity of available textbooks on the market which one is appropriate for a specific classroom and a group of learners. in order to evaluate elt textbooks, theorists and writers have offered different kinds of evaluative frameworks based on a number of principles and criteria. this study evaluate...

the primary goal of the current project was to examine the effect of three different treatments, namely, models with explicit instruction, models with implicit instruction, and models alone on differences between the three groups of subjects in the use of the elements of argument structures in terms of toulmins (2003) model (i.e., claim, data, counterargument claim, counterargument data, rebutt...